Desktop 813 Night Light Project

[Jeff K1NSS]

I got the idea from a picture posted by KB2VXA, of a Christmas tree topped by a lit-up 811A. That was shortly before Christmas. With little time left to do the same with a fallow 813 tucked away for a rainy day, I stepped back and thought Big Picture. How about a desktop 813 night light? Yeah, that's it, with a switched power take-off socket to remotely supply filament voltage to my tree toppper/vintage 813 valve NEXT CHRISTMAS. The pressure was off. But in the heat of the moment I Googled up the first apparently suitable filament transformer in sight and sent away toot sweet, before my Great Notion ebbed back to a Sea of Grave Reservations and I'd spend the rest of my life wondering what if?

The transformer arrived the day before Christmas. And while it was put aside for the duration, my project was never far from my thoughts. I thought I'd construct some kind of a housing for transformer to serve as a base for the pentode. Wood, metal, minimalist, artsy, fartsy, the base seemed a perfect storm of all but anything goes. Then I get a better idea. I could save myself a bunch of work if I could just find an appropriate box at my favorite local surplus store.

Well, I dropped by P&T Surplus in Kingston NY and found the box. Miraculously, it's a lamp power supply -- for a 6000 dollar Nikon microscope system boken up and sold a la carte. The supply was 20 bucks, and they threw in a couple of pin jacks and a genuine but empty Malden National box that I found in a tote of tubes.

So here's what I've got so far.

DSC_0194.jpg

Check this out. Before I opened it up at home, I figured I'd just gut it and use the nice solid front rocker switches and back outlets and whatnot.

DSC_0189.jpg

But check out what I found inside.

DSC_0190.jpg

Huh. Whole buncha voltages. No dedicated 10 tap, but 20 at 7A could be dropped to 10 with a resistor of suitable value and wattage, right? Don't everybody start throwing things. Of course, I could just remove the original transformer, mount mine in it's place, cut a hole in the top of the metal cabinet for the onboard tube socket, or make a wooden top, if I didn't feel like refinishing the metal case top. Everything looks pretty neat and tidy and secure, seems a shame to gut it, but perhaps some Islanders have some thoughts, once we get beyond the pointing and laughing. Have at it.

Jeff K1NSS

[Jeff K1NSS]

Oh, and another thing. The three pin, threaded LINE IN CONNECTOR, anybody know the number for that style, a searchable designator? There was none to fit it at the surplus store. Found some power connectors on line that look right, but the numbering seemed proprietary and varied and they were a little dear to just take a guess. Don't care about the 14 pinner.

[N8YX]

Oh, and another thing. The three pin, threaded LINE IN CONNECTOR, anybody know the number for that style, a searchable designator? There was none to fit it at the surplus store. Found some power connectors on line that look right, but the numbering seemed proprietary and varied and they were a little dear to just take a guess. Don't care about the 14 pinner.

I hink those are Amphenol "circular" series power connectors. Mouser and Digikey ought to have them, and possibly Surplus Sales.

[kf0rt]

I hink those are Amphenol "circular" series power connectors. Mouser and Digikey ought to have them, and possibly Surplus Sales.

That would be my guess too. Looks like an XLR connector, but threaded. Looks a lot like many of the ham microphone connectors, come to think of it.

[WØTKX]

XLR was my first guess, kind of "backwards" with the threaded collar? But the pin layout does not look right.

3 pn XLR is a triangle shoved to one side, and the lamp supply pins are arranged equilaterally and central.

[n2ize]

I'm dreaming of a Christmas tree lit up by a long string of 866 mercury vapour rectifiers.

[kb2vxa]

Uh oh, Dash! invaded your dreams.

Eh, don't wrack your brain over connectors, remove it and use a line cord and a grommet. You're headed in the right direction, gut the beast and put your transformer inside, you know the rest. Here's an interesting bit of food for your thought to chew on, a small lampshade. Steel is solderable so cutting off the wire that clips on the light bulb and soldering the contact from a plate cap to fit the tube to what's left finishes it off nicely.

I like what's on the back, a fuse for the mains and one for the 10V side. Then the AC outlets, one for the light strings on the tree and one for the tube come Christmas. Oh, I would put a mark over the one for the tube and a beacon on your antenna, I don't like unpleasant surprises and neither does Santa. (;->)

[n2ize]

I once built a "jacobs ladder" using a neon xfmr and tried using it was a night light. But the loud zorching and crackling of the arc traveling up the column kept me from sleeping.

[kb2vxa]

Er, mine set the lamp shade on fire.

[W3WN]

< snip >Oh, I would put a mark over the one for the tube and a beacon on your antenna, I don't like unpleasant surprises and neither does Santa. (;->)

Your timing was almost perfect. I had a hole to fill in the January newsletter, that photo fit just about perfectly! (Don't worry, I gave you credit as the source!)